Drawing instrument



Jan. 2, 923. i 1,440,625

. B. L. P!ERCE..`

DRAWING lrasRwAriruI FILEDIFE'B. 23, 1921.

/N VEN TOR: JB.L.P1ER c' ylll is limited the loop 30 thereovvith a lug 85 on the inner has a beveledarcuate edge or margin contacting With an oppositely beveled inner margin of said protractor segment. The slide rule is formed with a number of longitudinal slots 22 through which .pass screvvs 28l screwed into tapped holes in the clamping` segment 21. A latching plate 24 is mounted on the lower surface of the slide blade 15 adjacent the outer margin ofthe protractor segment 18and is ormedvvith one arcuate margin beveled to engage and lit snugly to the beveled outer margin ot' said segment. At its opposite margin ythe latching plate 24tis formed With integral upturned pins 25 lengagimg loosely in holes 26 termed in the blade 15. A thumb screw 27 is loosely mounted through the slide blade 15 and is screwed into a tapped vhole in the latching plate 24 and tightening movement of said screw tends to Jforce said plate toward the segment 18 and cause its beveled arcuate margin to engage and clamp on the beveled outer margin of said segment and also to force said segmenttoivard the clamping segment 21 and cause Aits beveled inner margin to clamp on the beveled outer margin of the latter member. Thus the pro# tractor segment is clamped firmly between the clamping segment 21 and the latching plate 2e, and pivotal movement ot the protractor members relative to the slide blade is prevented. The slide blade 15 is formed at one margin with a notch 28% and an indicator 28 overlying the scale 20., to indicate the degree of angularity of one oit said members relative to the other. The screvvs 23 may be loosened and the plate or segment 21 moved closer to the protractor segment to compensate tor Wear.

An operating lever 29 is formed at one end with a loop 3G engaging loosely the slide blade 15 and said lever extends laterally across the inner member ol the rectangular' frame l12 near the base rule- 10. That margin ofthe lever 29`i`arthest from the base rule 10 preferablyl is formed with an upturned ilange '31 for engagement by the ingers of the `operator in use, and a flanged member 32 preferably is secured to the vadjacent portion or" the base rule for a similar purpose. A top plate or housing member 33 is mounted onor fixed to the slide bearings 13, '14 and bridges the space between them, arching over the loop 30 of the operating lever. An expansive coil spring 34 is .liXed at one end to the lever 29 and at the opposite end to the inside of the top plate or housing' member 33, and tends to hold the free end of the lever away from the base rule 10, so that said" lever normally occupies a position obliquely to said rule and the slide rule l5 as shown. Movement of thelever 29 under the influence ol1 the spring by contact orn the outer end of posed angular faces ures margin olf tbe rectangular frame 12. The inside oli the loop 30 Yformed 'with op- 37 shown in .Figand 7, adapted :trictionallyto engage opposite side margins of the slide rule when the 'liree end oi the lever 29 is mov toward the base rule aga] e influence of the springl 3e. The diagonal line t in Figure 7 represents the line on which con* tact or the .loop 30 made ivith the blade 15 Whenmanual pressure is applied to the lever 29, and the diagonal line r presents the'line on which normal contactis .ade

under the influence ot the spring o vline a is of less length than the 'line Whenmanual pressure applic/.lato the lever the faces 36 and 37 oi the loop trictionally e the blade 15, so tnat continuation of the manual pressure between. the lever e and blade 10 causes th blade 15 to move up- Wardly relative to said blade 10.` .duch gagement ellects gripping contact ol.l the loop' 30 with the slide rule and preventsre ative sliding movement ot said rule and the operating men'iber. y l

rllo operate the device it is laid flat on a drawing table, board or sheet With the base rule indesired position, relative to a base line-or mark for instance. The protractor blade 17 is then used as a guide for drawing or laying oil'7 other lines, particularly for a series otH lines parallel with each yother and either parallel or aty a selected angle relative to the base line, or to the base rule 10. To move the protractor blade for successively forming such lines, the operator places his thumb against the flanged member 32 of the base Arule and lingers oit the same hand against the lever 29, or flange 31 29, by pressure with the lingers, to move said lever toward the base rule, the first ellect of such force being to move said lever to a position substantially parallel With said base rule., against the influencent the spring 3e. lWhen the lever reaches such position the angular faces 3, 37 of the loop4 3() `engage and grip` the slide blade 15, and further pressure on the lever and base rule l0 causes sliding movement 'of said slide blade7 and the members connected therewith, upwardly relative to the base rule. MeansA is provided to limit such movement, and such means preferably comprises an adjustable stop member carried by the rectangulary trame 12. screw 38 is arranged parallel With the slide rule and is journaled in bearings 39, lOkcarried by end members t theirame 12. .Il thumb Wheel or nut41 is mountedon and lined to the screw 38 for convenience in manually rotating it, and said Wheel preferably is `provided with a suitable graduated peripheral scale 2l-2 to indicate to the operator the amount or eX- 'tent oit rotation, as'by relation to a base mark or line 43, which may be .toi-med on one ot the bearings. rlhe lrnob 41 is adjustably secured to the screw 38 by means of a screw 41a. The adjustable stop member 44 preferably is formed oi` a strip of metal bent around the screw 58 and retained thereon by means ot a screw 44a. rlhe'se screws may be employed in adjusting and setting the several members in proper relation to the graduated scales A stop member is threaded on the screw 3S and is adapted to be engaged by that side of the loop 30 nearest the base rule 10, that is by the side opposite to the one which engages the lug Such engagement limits sliding movement ot tlieslide blade relative to the base rule as above described, and the amountoi such movement may be gaged and adjusted by rotating tlie screw 38 in either direction to advance or retract the stop member 44 relative to the base blade. rlhe stop member 44 is formed at its outer end with lugs 45, 46 slidingly engaging upper and lower faces respectively ot trie outer side member of the trame 12. to prevent rotation of the stop member on the screw, thus causing' it to move longitudinally when the screw is rotated. The uppermost lug 45 is iormed` with an index mark 47 and the adjacent member ot the frame 12 is formed with a graduated scale 48, to indicate the amount ot movemento'l` the stop member relative to said 'frame and the base rule.

Adjusting; plates 49, 50 are provided for the respective slide bearings 13, 14. Each plate 49, 50 is set into a recess 51 in an end member of the trame 12 andhas one inclined tace engaging' an inclined and beveled face ot said recess, which inclined and beveled faces are on the sides of the plates farthest from the bearings 13, 14. rl`he opposite margin ot each plate 49. 50 is straight and parallel and in contact with the adjacent margin ot the slide rule 15: said plates preterably being on opposite sides of said rule. A screw 52 is loosely mounted through `each slide bearing` 13, 14 and screwed into the adjusting; pla-te 49 or 50 therebeneath. A pencil end or stylus may be employed to slide either of said adjustingl plates along its recess 51 in either direction.. when the screw 52 is loosened and by the relation of the inclined tace of said adjusting plate to force or release the slide blade to desired position with respect to the graduated scale ot the base rule and at right angles to it. Then the screws 52 are tightened to hold the adjustable parts immovable against the slide rule when pressure is applied to lever 29 or when the protractor blade is used as a straightedgre for a marking or cutting tool. ln such adjusting operation the plates 49, 50 have the functions of wedges between the inclined faces ot the recesses 51 and the opposed margins of the slide rule, and may be used selectively or conjunctively` to secure and maintain the proper position ot the slide rule perpendicular to the base rule.

Th base rule 10 and frame 12 be provided with projecting teeth on their lower taces,` to engage the paper or board and prevent lslippingot the instrument in use. The outer end of the base rule may be formed with a hole to receive a thumb tack or other securing device at times when desired.

rlhis instrument may be used in lieu of T- square and triangles and be employed as. a guide in drawing,` or laying,` o all lrindsvolt straight lines. either vertical, horizontal or oblique. 1t is very convenient tor crosshatching, as a series olf lines may be drawn very rapidly and uniformly spaced by the useoie the protractor blade and operating lever, and said lines may be parallel with each other and with the base rule, or at any desired angle relative to the latter. The

. degree of spacing' is of course determined by `manipulation of the stopkmember 45 through the screw 40, anl the amount of such spacv ing;- may be determined to very small fraction of an inch, by means of the scales 42 and 48. rlhe graduation ot the scale 48 and its relation'to the marlr 47 ot thestop member is in accord with the threads ot the spacing,` adjustment screw 38; and as the number of such threads per' inch are known, the

desired :traction of an inch may bedetermined.

The instrument maybe used `for dividing' a given space into a given number of equal parts, after the manner of Compasses or dividers, but without leaving` ,any objectionable marlrs or holes in the paper or board. 1t is alsovuseful forv laying ofi scores for manuscript sheet music, it being an easy matter to omit certain lines. as between successive staffs, without disturbing the continuity and accuracy ofthe spacing.

@ther uses of theinstrument will be readily understood or developed by those skilled in the art. H

l Iclaim as my inventionl. A drawing instrument, comprising a base rule formed with. slide bearings, a slide rule slidably mounted in. said bearings and extending at an angle to said base rule, a protractor rule secured to said slide `rule and extending; at an angle thereto, and an operating member adapted tor manual ac` tuation to engage said slide rule and Cause step-by-step sliding movement thereof.

2. A drawing instrument, comprising a base rule formed with slide bearings, a slide rule slidably mounted in saidbearings and extending at an angle to said rule, a protractor rule secured to said slide rule and extending at an angle thereto, and an operatina' member vtormed with a loop loosely engaging said slide rule, said member being,`

adapted tor manual movement in one direction to cause said loop to trctionally enanl cause sliding movement of said slide rule.

3. drawing instrument, comprising a base rule formed With a slide bearing, a slide rule slidably mounted in said bearing and extending at an angle thereto, a protractor rule secured to said slide rule and extending at an angle thereto, and an operating' member formed with a loop loosely embracing said slide rule, said meniber being adapted tor manual movement in one direction to cause said loop to irictionally engage and effect sliding movement oit said slide rule, together with yielding means tending to move said operating member in the opposite direction.

4l. A drafting instrument, comprising a base rule formed with a slide bearing, a slide rule slidably mounted in said bearing and extending at an angle to said base rule, a protractor rule secured to said slide rule and extending at an angle thereto, an operating member adapted tor manual movement in one direction to engage and cause i sliding` movement of said slide rule, yielding means being provided for moving said operating member in the opposite direction, and adjustable means for limiting the sliding movement of said slide rule.

5. A. drafting instrument, comprising a base rule formed with a slide bearing, a slide rule slidably mounted in said bearing and extending at an angle to said base rule, a protractor rule secured to said slide rule and extending at an angle to said slide rule, a spring-pressed operating member formed with -a loop loosely embracing said slide rule, said member being adapted for manual movement against the pressure of said spring to cause said loop to trictionally enand eiilect sliding movementl of said slide rule, and a stop adjustably carried by said base rule and adapted tor engagement by said loop to limit sliding movement of said slide rule.

6. A drafting instrument, comprising a .naaaeee base rule formed with a slide bearing, a slide rule slidably mounted in said bearing and extending at an angle to said base rule, a protractor rule secured to said slide rule and extending at an angle thereto, an operating member termed with a loop loosely embracing said slide rule, said member being adapt ed for manual movementin one direction whereby said loop engages and causes sliding` movement ot said slide rule, a screw carried by said base rule, and a stop adjustably mounted on said screw and adapted for engagement by vsaid slide rule to limit the sliding movement thereof.

7. ln a drafting instrument, a'base rule, a slide bearing thereon, and a slide rule slidably mounted in said bearing, said base rule being formed with a recess at one side of said slide bearing and having an inclined tace opposite thereto, an adjusting plate formed with an inclined face engaging the inclined tace of said recess and engaging at its opposite margin a margin of said slide rule, and a screw mounted through said bearing and seated in said adjusting plate, whereby the angularity ot said rules may be adjusted by movement ot said adjusting plate.

8. ln a. drafting instrument, a rule and a second rule arranged at an angle to the rst rule, the second rule being formed With a protractor ot semi-annular term having beveled edges, a segment adjustably secured to the first rule and having its arcuate margin beveled and in engagement with the inner margin of said protractor, a clamping plate carried by the first rule and having an arcuate beveled margin in contact with the outer margin of said protra'ctor, said plate being formed with teeth loosely seated in said lirst rule, and a. screvvfpassing loosely through said first rule and seated in said plate.

Signed at Des Moines, in the county of Polli and State of lovva, this 28th day of December, 1920.

nnnminn tenor' Pinnen 

